If you are on a windows comp (which i suspect you of because of your mention of right click):
You need to decompress the plugins that you download using Stuffit 7.5 (not 8.0), and then drag+drop the created file onto the plugin converter in your ev nova folder. Then drag the .rez file that the converter created into your nova plugins folder.
You must not allow the resource.map file to be in the nova folder. It will kill you.
As for not being able to download, you need to be more spesific. It is likely that any problem related to being able to download plugins is a symptom of a wider problem with your browser (though because of the frequently crossplatform aspect of plugin dls, that may be part of the issue as well). We cant help in anycase if you dont tell us more details.
No matter what OS you are on, though, You must be registered to use plugins. You propably knew this, but i figured i would cover all the bases.
-Az
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